NEW DELHI/KOLKATA, May 23 (Reuters) - India began counting hundreds of millions of votes in its general election on Thursday, with a coalition led by Prime Minister Narendra Modi's party taking an early lead, TV channels and India's Election Commision said.

The National Democratic Alliance (NDA), led by Modi's Hindu nationalist Bharatiya Janata Party (BJP), is expected to surpass the 272 seats needed to command a majority in the lower house of parliament, six of seven exit polls showed on Sunday.

The NDA led in 235 seats, with the opposition United Progressive Alliance ahead in 95, at 9 a.m. local time (0330 GMT), about an hour after the counting of about 600 million votes began, Indian TV channel NDTV said.

Official data from India's Election Commission showed the BJP ahead in 101 seats, with the main opposition Congress Party ahead in 40. There are 542 seats available.

Trends are expected to be known by noon and final results are due by Thursday evening.

The NDA's predicted margin of victory is larger than surveys indicated in the run-up to the vote, when most polls showed it would be the largest alliance but would fall short of an overall majority.

Modi was under pressure when he began campaigning, losing three state elections in December amid rising anger over farm prices and unemployment.

However, campaigning shifted towards India's relationship with nuclear-armed rival Pakistan after a suicide car bomb killed 40 Indian police in the contested Kashmir region in February, to the benefit of the right-wing BJP, analysts said.

"National security became the discussion," said Harsh Pant, a political analyst at the Observer Research Foundation think tank in New Delhi. "It allowed the BJP to shirk some issues where it was weak."

The BJP has also capitalised on the star power of Modi, a frenetic campaigner, as well as superior financial resources.

It outspent Congress by six times on Facebook and Google advertising, data showed, and by as much as 20 times overall, sources told Reuters earlier this month.

"The longer election certainly helps Modi: he loves contact with the people," Pant said. "The BJP's electoral machinery is also much more effective on the ground."

VICTORY PREPARATION

Police guarded voting centres in West Bengal on Thursday, where campaigning had turned violent as the BJP tried to take seats from the Trinamool Congress, a powerful regional party.

"Wherever we go people are talking about a BJP wave in Bengal," said Tapas Das, a taxi driver in the state capital, Kolkata. "Everyone wants to see a change."

Several opposition leaders attempting to unseat Modi have urged voters to wait for the final results, calling the exit polls "gossip".

The opposition alliance has also protested to India's Election Commission over the electronic voting machines (EVMs) used in the count, which they alleged could be tampered with, and requested a delay to counting while votes were tallied with a backup paper audit trail.

The commission rejected the opposition's demands on Wednesday.

Around 500 masked people carrying guns and machetes attacked a polling team and forcibly took away EVMs in the remote northeastern Indian state of Arunachal Pradesh, Reuters reported on Wednesday, although the election was widely considered by international observers to be free and fair.

The NDA held a meeting on Tuesday, at which Modi was garlanded with flowers by members of the alliance, to discuss its policy agenda for its second term in power. It has promised to double farmers' income and boost infrastructure spending over the next five years.

Indian stocks posted their biggest gain since September 2013 on Monday and could rally further on Thursday if the trend is confirmed, according to a Reuters poll.

"Markets will heave a big sigh of relief as it favours continuity and familiarity in terms of roll-out of policies," said Ajay Bodke, CEO at financial services firm Prabhudas Lilladher.

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